Another very widespread delusion productive of great harm is that cancer is constantly associated with wasting, and makes rapid progress. These two symptoms are constantly associated with the disease in its latest stages but are not seen at all in early cases.

One frequently hears people say that cancer is contagious, and also that it is hereditary. These two popular conceptions probably have the same basis. As we have seen, cancer is a very common disease, and it would be strange indeed if, putting all question of relationship on one side, we were not to see it quite commonly occurring in one or more members of the same family, and if occasionally we did not find a house in which each successive occupant for some years had cancer. I will leave it to the mathematicians to work out the probability of cancer occurring more than once in any given family. The necessary figures are easily obtained from the Registrar-General’s office. As far as I know, there is nothing truly in the nature of what may be called evidence in support of either of these notions.

Time after time people have described parasites of some kind as associated with cancer, but none of them has yet been made to answer to any of the tests necessary to establish anything more than a casual correlation. It may turn out to be that the causal agent in cancer formation is a parasite either visible under the microscope, or, what is more likely, belonging to the group of ultravisible, or filter-passing, organisms; but even if this be so, there are two other factors of immense importance, found so constantly associated with the disease, that their significance cannot be underestimated by anyone whose outlook is any wider than that of the mere purveyor of prescriptions.

These two factors may be considered in a little more detail, as they are of importance with regard to the question of prevention. They are (1) the presence of an acid environment, and (2) what, for want of a better term, may be called chronic irritation. Whatever the prime cause may turn out to be, these can never be left out of account in any consideration of aetiology, and even if some specific cause is found, the discovery will not shake the validity of my thesis.

For two thousand years people have speculated about the origin of cancer. Galen held a theory somewhat analogous to the present Chinese doctrine of the yin and the yang; he taught, in essence, that some kind of “ch’i” had got at loggerheads with its fellow gases, and that the result was a general disturbance of bodily functions. Paracelsus thought that the salt balance of the body was upset, and textbooks still sometimes put this into modern medical terminology, saying that the balance of power between different types of cells is disturbed. This may or may not describe what happens, but it is a long way from explaining it.

In the sixteenth and seventeenth centuries cancer was often referred to as an “act of God” in punishment for sin. For instance, cancer of the tongue was said to afflict those who spoke against the Church, a view that the Church, not always strictly scientific in interpretation of phenomena, did not discourage.

Here is a translation which Sir D’Arcy Power has made from Paul de Sorbant, a German physician writing in 1672, in his Universa Medicina. “We saw”; he says, “an ulcer of the tongue degenerating into cancer in the noble baron Vertemali, which caused such a haemorrhage from destruction of the sublingual arteries and veins that the patient was suffocated. He recognised with great penitence that the cause of this cancer was a divine punishment because he had often abused the clergy.” Benetus, about the same time, in his book called Medicinae Septentriniolanus Collatitia, describes a case of what he calls “Tumor Linguae Miraculosa.” Here is a translation of part of it. “There was lately a certain baron who had a very poisonous tongue. He not only directed his jibes against all and sundry, but he kept his most venemous shafts for the clergy and those who devoted themselves to God’s service. He was caught at last in the very act, by a holy brother of good repute as he was pealing this cursed bell, who said to him: ‘Your foul tongue has overlong deserved that punishment from an offended God which it will shortly receive.’ The Baron went off undismayed, but a few days afterwards a small swelling began to grow on the side of his tongue. Little by little it increased in size until it became an inoperable cancer, and at length the tongue having become incurved, twisted and drawn back to his throat, miserably afflicted, but penitent and confessed, he was summoned before the Great Judge who calls his servants to a most strict account.”

This may all seem very far away and out of contact with our present-day thought, but only two years ago a dear old lady sent to the Cancer Hospital Research Department two pages of closely written typescript, the gist of which was that she was withdrawing her usual annual subscription, as, after giving the matter a great deal of thought, she had come to the conclusion that cancer was caused by the consumption of alcohol. So she proposed to forward her usual subscription to the local Temperance Society which really was striking at the root of the problem! The Secretary wrote and pointed out that cancer is very common in cats who are strict prohibitionists! The old lady did not reply!

Let us come back again from theory to fact, and consider some of the factors which we know constantly to be associated with cancer, and which we are justified in regarding as being, in many cases, more than predisposing causes.

The most important of these is chronic irritation. We find that almost every cancer is preceded for a longer or shorter period by what may be called a precancerous condition. The more our knowledge increases the more we are finding out that this holds good.